The present invention relates to the field of sound spatialization.
Recently, the present applicant has proposed a system for spatialization of sound whereby sound signals are spatialized to remain constant when played over headphones and in the presence of head movement detected by a headtracking device.
In other known arrangements, principal component analysis is utilized to alter the HRTF functions so as to simulate the effect of sound movements.
Often, there are extremely subtle effects at play when a listener attempts to locate sounds spatially.
It is an object of the present invention to provide for an improved form of spatialization of sounds in a headtracked environment.
In accordance with a first aspect of the present invention, there is provided an apparatus for implementing a Head Related Transfer Function on an input audio signal in a headtracked listening environment comprising: a series of principle component filters attached to the input audio signal and each outputting a predetermined simulated sound arrival; a series of delay elements each attached to a corresponding one of the principle component filters and delaying the output of the filter by a variable amount depending on a delay input so as to produce a filter delay output; a summation means interconnected to the series of delay elements and summing the filter delay outputs to produce an audio speaker output signal; headtrack parameter mapping unit having a current orientation signal input and interconnected to each of the series of delay elements so as to provide the delay inputs.
Each of the delay elements further can include a gain factor unit adapted to multiply the filter delay output by an amount determined by a gain input signals to the delay element and the headtrack parameter mapping unit output a gain input signal to each of the delay elements.
In accordance with a further aspect of the present invention, there is provided a method for implementing a Head Related Transfer Function on an audio signal in a headtracked listening environment, the method comprising the steps of: filtering the audio signal by a series of principle component filters to produce a series of filtered component outputs; delaying each of the filtered component outputs by an amount dependant on a current listener""s head orientation to produced delayed principal components; combining the delayed principal components to form an output audio speaker signal.